1. Field of the Invention
The present invention relates to a method and apparatus for adjusting a brightness of a display screen. More particularly, the invention relates to a method and apparatus for adjusting the brightness of a display screen, such as a LCD (Liquid Crystal Display) screen, based on whether an apparatus to which the display screen is connected, such as a computer, is performing display intensive operations, as determined, for example, by CPU usage amount, type of CPU usage, or usage of peripheral devices, such as a modem or memory device.
2. Background of the Related Art
FIG. 1A shows an example of a system which may utilize a typical method for adjusting a brightness of a display screen. In this example, the system is a laptop computer 10, with an LCD display screen 30. The laptop computer 10, has a port 20, to receive the output of an AC adapter 90. The laptop computer 10 is also provided with a battery 100, as an internal source of power. User signal inputs are entered into the system through a keyboard 60 and a mouse 70. The laptop computer 10 may incorporate various memory devices such as an internal hard disk drive 80, an external hard disk drive 110, a CD-ROM or DVD drive 40, and a modem 50.
FIG. 1B is a flow chart illustrating a typical method for adjusting a brightness of a LCD screen or other type of display screen in accordance with the related art. According to the method illustrated in FIG. 1, a brightness of a LCD screen is adjusted in accordance with a type of power source of the machine, such as an internal power source or an external power source. After the computer system is turned “ON” in step S10, a central process unit (CPU) to which the LCD screen or other type of display screen is connected executes instructions to determine whether the power supplied to the system is supplied through an external power source, such as an AC adapter, or by an internal power source, such as a battery, in step S11. If it is determined in step S11 that power is supplied to the system through an external power source, the brightness of the LCD screen or other type of display screen is maintained at its optimum viewing brightness in step S12. If it is determined in step S1 1 that power is supplied to the system from an internal source, such as a battery, the brightness of the LCD screen or other type of display screen is reduced in step S13. In other words, when the system is being powered by a limited power source, such as a battery, the brightness of the LCD screen or other type of display screen can be reduced to conserve power.
An operating system used by the CPU, for example, Windows 98, may include a function for determining whether the CPU is in use. When the user does not operate the computer for a pre-determined period of time, the computer switches into a power save mode automatically in accordance with settings chosen by the user to further reduce power consumption. Such a determination can be based on lack of user input, such as from a mouse or keyboard.
However, in the related art as described above, when the user watches a movie on the computer by executing a video file or an internet broadcast, because there are no inputs from the mouse or keyboard, the operating system determines the computer is not in use. The operating system thus dims the display screen and the user can not watch the movie. In addition to dimming the screen, to further conserve power when the user does not use a user signal input apparatus, such as a keyboard or mouse, the system is converted from an “ON” state into an “IDLE” state, in which state the clock rate of the CPU is reduced. With the clock rate reduced, the display screen image is not updated as frequently, and the video impaired. However, despite no keyboard or mouse activity, the user may be using the machine to watch, for example, a movie or an internet broadcast, and not want reduced video performance.